msm: cvp: Relocate Synx init/uninit calls

Move synx init/uninit calls to session creation and
deletion functions to avoid racing between synx release and
uninit.

Change-Id: I57d0a3e621f1fe7bacd811c03f89d754b4255b8e
Signed-off-by: George Shen <sqiao@codeaurora.org>